Wikileaks founder Julian Assange is pictured through the heavily tinted windows of a police vehicle as he arrives at Westminster magistrates court today. Photo: AFP/Getty Images

LONDON — A British judge granted Julian Assange bail on Tuesday but the WikiLeaks founder will remain in custody for at least another 48 hours after Swedish prosecutors said they would challenge the decision.

Assange, a 39-year-old Australian, has already spent a week in a U.K. jail following his surrender to police in a Swedish sex-crimes investigation. He denies any wrongdoing and his lawyers say he plans to fight Sweden’s extradition request.

Britain’s High Court will hear the Swedish appeal, although it wasn’t immediately clear when.

Assange’s lawyer Mark Stephens said his client’s relief at the bail decision had already evaporated, calling it “unfortunate” that “the Swedes won’t abide by the umpire’s decision.”

“They clearly will not spare any expense but to keep Mr. Assange in jail,” Stephens told journalists outside the City of Westminster Magistrates’ Court in London. “This is really turning into a show trial.”

Celebrity supporters in the court and pro-WikiLeaks protesters outside the building had earlier cheered Judge Howard Riddle’s decision to free Assange.

Assange’s mother Christine, who was flown to Britain by Australian media outlets, watched the hearing nervously from the public gallery but gave a huge smile as the judge announced his decision.

“I just want to thank everyone who’s turned up to show their support and who’s taken an interest,” Christine Assange said.

Under the ruling Tuesday, Assange would be subject to strict bail conditions. Stephens said the court was demanding 200,000 pounds ($316,000) in bail up front before Assange could be freed. He would also have to wear an electronic tag, live at a registered address, report to police every evening and observe two four-hour curfews each day.

Several wealthy supporters have put up a total of 240,000 pounds ($380,000) as a guarantee for Assange, his lawyers said.

Assange’s next court appearance was set for Jan. 11, ahead of a full hearing on Feb. 7 and 8.

Lawyer Gemma Lindfield, acting for Sweden, had asked the court to deny Assange bail because the allegations in Sweden were serious, Assange had only weak ties to Britain and he had enough money “to abscond.”

At a court hearing last week, Lindfield said Assange is accused of rape, molestation and unlawful coercion. She told the court one woman had accused Assange of pinning her down and refusing to use a condom on Aug. 14 in Stockholm. That woman also accused of Assange of molesting her.

A second woman has accused Assange of having sex with her without a condom while he was a guest at her Stockholm home and she was asleep.

In Sweden, a person who has sex with an unconscious, drunk or sleeping person can be convicted of rape and sentenced to up to six years in prison.

Assange denies the allegations and has not been charged in Sweden. His lawyers say the allegations stem from a dispute over “consensual but unprotected sex.”